The F18 rules don't specific prohibit "lifting foils" but as Wouter pointed out, they do specify that the rudders and daggerboards must be in the "vertical plan of the hulls". There is no restriction for adding a second daggerboard or foil further forward of the main beam but I suspect one could make a strong argument that such a foil would not be in the spirit of the rules. In my opinion, it is very likely that the International F18 rules committee would frown on such a development. Besides that, it sounds like Gino is pulling your leg. There is a new Nacra F18 on the way - but a retractable forward bow lifting foil?